Shaw will get killed if he tries to fight anyone—especially Mariusz. Mariusz is far from anything special but he's a legit athlete who can do the basics, whereas Brian is one of the most maladroit oafs I've ever seen, with almost zero ability in this sport. He's no doubt banking on using his massive size to pin a guy to the deck, but it's not happening against a heavyweight with basic wrestling skills. He's just going to eat punches until the ref saves him.
Edit: Just realised I'm totally rambling in the wrong thread. Did I imagine things or was there not supposed to be a fight on the horizon with Shaw and Mariusz?